In general, an automobile drives wheels via a crankshaft, an input shaft of a transmission, a drive shaft, or components mounted thereon and rotating integrally, by driving an engine. When the engine is driven, it is known that torsional vibrations corresponding to the number of cylinders of the engine are transmitted to the crankshaft or the like, causing many problems such as reduction of ride comfort and occurrence of abnormal noise of the transmission. Therefore, a number of dynamic dampers attached to a rotating body such as a crankshaft or the like to absorb or damp the torsional vibration of the rotating body have been proposed. As one example thereof, there is a centrifugal pendulum damper that damps torsional vibrations of a rotating body by a pendulum movement of the mass body with torsional vibration of the rotating body (see, for example, Patent Document 1).
The centrifugal pendulum damper disclosed in Patent Document 1 includes a pendulum chamber in which a mass body is swingably accommodated in a rotating direction of the rotating body, and a guide groove for guiding the rotating shaft of the mass body in the rotating direction of the rotating body, and supports the mass body to be movable in a radial direction of the rotating body. As a result, a trajectory of the position of the center of gravity due to the pendulum movement of the mass body is assumed to be a cycloid curve or the like. With this configuration, vibration damping performance independent of the magnitude of the amplitude of the mass body is obtained.
Further, if the frictional torque generated between the pendulum mass body and the pendulum support body is large, the centrifugal pendulum damper may hinder the function of the pendulum. Therefore, various techniques have been proposed to prevent the vibration absorbing function of the pendulum from being impaired due to the frictional torque.
For example, in a centrifugal force pendulum apparatus of Patent Document 2, a pendulum mass body is supported via a rolling element so as to be movable relative to a pivotable pendulum support body. Between the pendulum support body and the pendulum mass body, there is provided a guide part which at least locally reduces an axial interval between them. According to this centrifugal force pendulum apparatus, a tilting angle of the pendulum mass body can be reduced by the reduction in the gap distance between the pendulum mass body and the pendulum support body, and undesirable tilting of the individual pendulum mass body is avoided. As a result, the stability of the centrifugal force pendulum as a whole is improved.
Further, in a flywheel of Patent Document 3, a rolling chamber is formed in a rolling chamber constitution body fixed to the flywheel main body. The rolling chamber accommodates a damper mass that performs a centrifugal pendulum movement, while rolling in synchronism with the cycle of torque fluctuation of the rotation drive system to which the flywheel body is fixed. Convex portions continuous in a circumferential direction are formed on a circumferential surface of the damper mass. Further, on the rolling surface of the rolling chamber, a concave portion that meshes with the convex portion and continues in the rolling direction is formed. In the flywheel, the convex portion and the concave portion constitute a guide rail structure. According to this flywheel, since the meandering of the damper mass is prevented by the guide rail structure, a contact area between a side surface of the damper mass and an inner surface of the rolling chamber is reduced. As a result, the frictional torque generated in the direction of preventing the centrifugal pendulum movement of the damper mass can also be reduced.